Pollen–style compatibility in cashew (Anacardium occidentale L.)

The role of pollen–stigma interaction and pollen tube growth as a measure of genetic compatibility was studied in eleven clones of cashew under a tropical rainforest ecology in Southwestern Nigeria between 1999 and 2002. Diallel cross of the clones showed that 55.00% of the cross-pollinated crosses showed high pollen cross-compatibility (CC) indicating moderate genetic distance in the population. About 54.55% of the clones showed evidence of self-compatibility, therefore confirming that cashew is self-fertile. Cytological examination however suggests possible postzygotic self-incompatibility in the crop as no evidence of tube growth inhibition was recorded in both cross- and self-pollinated styles. Correlation between maternal compatibility (pollen recipients) and fruit set shows that more attention need to be focused in this direction during selection. Based on the data from this study, the use of combinations of floral quality characteristics like high pollen fertility, prolific flowering, and high flower sex ratio plus high cross-compatibility as reliable selection criteria for cashew yield improvement is therefore suggested.